Rectifiers are electronic circuits or electronic devices that allow a current to flow in a first direction, while preventing a current to flow in an opposite second direction. Such rectifiers are widely used in a variety of electronic circuits in automotive, industrial and consumer applications, in particular in power conversion and drive applications.
Conventional rectifiers can be implemented with a diode that conducts a current when forward biased and that blocks when reverse biased. A diode, however, causes relatively high losses when forward biased. These losses are proportional to the current through the diode. In particular in power conversion application or power supply applications in which high current may flow through the rectifier, significant losses may occur. Further, due to reverse recovery effects, a diode (power diode) used in power conversion or drive applications does not immediately block when it changes from the forward biased state to the reverse biased state, so that there may be a time period in which a current flows in the reverse direction.
A rectifier can also be implemented with a MOSFET (power MOSFET) and suitable drive circuit for the MOSFET. A conventional power MOSFET includes an integrated diode, known as body diode, that is effective between a drain terminal and a source terminal of the MOSFET. By virtue of this diode a MOSFET always conducts a current when a voltage is applied between the drain and source terminals that reverse biases the MOSFET. In an n-type MOSFET (p-type MOSFET), a voltage reverse biasing the MOSFET is a positive source-drain voltage (negative source-drain voltage). The drive circuit switches the MOSFET on each time the MOSFET is reverse biased. The losses occurring in a MOSFET in the on-state are lower than losses occurring in a diode under similar operating conditions. However, power MOSFETs, that may be used in rectifiers, in drive applications or an power conversion applications, may have a significant output capacitance that needs to be charged/discharged each time the MOSFET is switched on/off. This capacitance causes switching losses and switching delays.
There is therefore a general need to provide a circuit arrangement with a rectifier circuit having reduced losses.